Why won't the purchase GUI remove when clicking OK?

I have a bit of basic code to enable players to purchase a gamepass in-game. The code below is in a script inside a click detector.

function onMouseClick(player)
if player.UserId >0 then
local MarketplaceService = game:GetService("MarketplaceService")
local productId = 326358490
MarketplaceService:PromptPurchase(player, productId)
end
end
script.Parent.MouseClick:connect(onMouseClick)

This all works fine, and displays the GUI saying that I already have purchased the gamepass. However, when you try to click OK to remove the message, it doesn't remove. Is this due to my script or a ROBLOX core script? I'd appreciate any help.